BD Merit - Freelancing, BCS, Bank, Primary, Admission, NTRCA

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Answer: Option A

Explanation:

{ব্যাসার্ধ  r হলে ক্ষেত্রফল=πr}^{2} ∥ (r + n) ∥ ∥ = π {(r + n)}^{2} প্রশ্নমতে, 2 \times {πr}^{2} = π {(r + n)}^{2} \Rightarrow 2 r^{2} = {(r + n)}^{2} \Rightarrow \sqrt{2} r = r + n \Rightarrow \sqrt{2} r - r = n \Rightarrow r (\sqrt{2} - 1) = n \Rightarrow r = \frac{n}{\sqrt{2} - 1} \Rightarrow r = \frac{n (\sqrt{2} + 1)}{(\sqrt{2} - 1) (\sqrt{2} + 1)} \Rightarrow r = \frac{n (\sqrt{2} + 1)}{2 - 1} ∴ r = n (\sqrt{2} + 1)

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